In July 2006, a major international conference was held at the Perimeter Institute for Theoretical Physics, Canada, to celebrate the career and work of a remarkable man of letters. Abner Shimony, who is well known for his pioneering contributions to foundations of quantum mechanics, is a physicist as well as a philosopher, and is highly respected among the intellectuals of both communities. In line with Shimony's conviction that philosophical investigation is not to be divorced from theoretical and empirical work in the sciences, the conference brought together leading theoretical physicists, experimentalists, as well as philosophers. This book collects twenty-three original essays stemming from the conference, on topics including history and methodology of science, Bell's theorem, probability theory, the uncertainty principle, stochastic modifications of quantum mechanics, and relativity theory. It ends with a transcript of a fascinating discussion between Lee Smolin and Shimony, ranging over the entire spectrum of Shimony's wide-ranging contributions to philosophy, science, and philosophy of science.

ROSAT Observations G. HASINGER Max-Planck-Institut flir extraterrestrische Physik, D-85740 Garching, Germany Abstract. This review describes the most recent advances in the study of the extragalactic soft X-ray background and what we can learn about its constituents. The deepest pointed observations with the ROSAT PSPC are discussed. The logN-logS relation is presented, which reaches to the faintest X-ray fluxes and to the highest AGN surface densities ever achieved. The N(>S) relation shows a 2 density in excess of 400 deg- at the faintest fluxes and a flattening below the Einstein Deep Survey limit. About 60% of the extragalactic background has been resolved in the deepest field. Detailed source spectra and first optical and radio identifications will be discussed. The results are put into perspective of the higher energy X -ray background. Key words: X-rays, background radiations, active galactic nuclei. 1. Introduction The extragalactic X-ray background (XRB), discovered about 30 years ago, has been studied extensively with many X-ray experiments, in particular with the satel lites HEAO I and II (see ego Boldt 1987) and with ROSAT (e. g. Hasinger et aI. , 1993). Figure 1 shows a compilation of some of the most recent spectral measure ments for the X-ray background. Over the energy range from 3 to about 100 keY its spectrum can be well approximated by an optically thin thermal bremsstrahlung model with kT ~ 40 keY, while at lower X-ray energies a steepening into a new component has been observed observed (e. g.

The first Asia-Pacific Conference on Few-Body Problems in Physics took place from August 23 to August 28, 1999, at the Noda campus of the Sci ence University of Tokyo in Noda-city and Sawayaka Chiba Kenmin Plaza in Kashiwa-city, a suburb of Tokyo close to the Narita-Tokyo International Air port, with the Frontier Research Center for Computation Sciences (FRCCS) of the Science University of Tokyo as the host institute. The High Energy Accel erator Research Organization (KEK), the Institute of Physical and Chemical Research (RIKEN), the Research Center for Nuclear Physics (RCNP)-Osaka University, the Physical Society of Japan, and the Association of Asia Pacific Physical Societies (AAPPS) supported this conference. The conference was initiated in the Asia Pacific area as a counterpart to the successful European Conference on Few-Body Problems in Physics (APFB99), in addition to the International Few-Body Conference Series and the Few Body Gordon Conference series in North America. The Physics of Few-Body Problems covers, as is well known, systems with finite numbers of particles in contrast to many-body systems with very large numbers of particles. Therefore, it covers such wide fields as mesoscopic, atom-molecular, exotic atom, nucleon, hyperon, and quark-gluon physics, plus their applications."

The Olympia conference Frontiers of Fundamental Physics was a gathering of about hundred scientists who carryon their research in conceptually important areas of physical science (they do "fundamental physics"). Most of them were physicists, but also historians and philosophers of science were well represented. An important fraction of the participants could be considered "heretical" because they disagreed with the validity of one or several fundamental assumptions of modern physics. Common to all participants was an excellent scientific level coupled with a remarkable intellectual honesty: we are proud to present to the readers this certainly unique book. Alternative ways of considering fundamental matters should of course be vitally important for the progress of science, unless one wanted to admit that physics at the end of the XXth century has already obtained the final truth, a very unlikely possibility even if one accepted the doubtful idea of the existence of a "final" truth. The merits of the Olympia conference should therefore not be judged a priori in a positive or in a negative way depending on one's refusal or acceptance, respectively, but considered after reading the actual of basic principles of contemporary science, new proposals and evidences there presented. They seem very important to us.

The NATO Advanced Study Institute "Cosmological Aspects of X-Ray Clus ters of Galaxies" took place in Vel en, Westphalia, Germany, from June 6 to June 18, 1993. It addressed the fruitful union of two topics, cosmology and X-ray clus ters, both of which carry substantial scientific weight at the beginning of the last decenium of the last century in the second millenium of our era. The so far largest X-ray "All-Sky Survey," observed by the ROSAT X-ray satel lite, and ROSAT's deep pointed observations, have considerably enlarged the base of X-ray astronomy, particularly concerning extragalactic sources. Cosmology has gained significant impetus from the large optical direct and spectroscopic surveys, based on high quality 2-dimensional receivers at large telescopes and powerful scan ning devices, harvesting the full information 1 content from the older technique of employing photographic plates. Radioastronomy and IR-astronomy with IRAS, as well as r-astronomy with GRO, continue and strengthen the role of extragalactic research. The rapidly growing computer power in data reduction and data storage facilities support the evolution towards large-number statistics. A most significant push was given to early cosmology by the needs of physics in trying to unravel the nature of forces which govern our material world. The topic of the ASI was chosen because it opens new vistas on this for ever new problem: the universe. Clusters of galaxies probe large-scale matter distributions and the structure of space-time."

In this book are reported the main results presented at the "Fourth International Workshop on Data Analysis in Astronomy," held at the Ettore Majorana Center for Scientific Culture, Erice, Sicily, Italy, on April 12-19, 1991. The Workshop was preceded by three workshops on the same subject held in Erice in 1984, 1986 and 1988. The frrst workshop (Erice 1984) was dominated by presentations of "Systems for Data Analysis"; the main systems proposed were MIDAS, AlPS, RIAIP, and SAIA. Methodologies and image analysis topics were also presented with the emphasis on cluster analysis, multivariate analysis, bootstrap methods, time analysis, periodicity, 2D photometry, spectrometry, and data compression. A general presentation on "Parallel Processing" was made which encompassed new architectures, data structures and languages. The second workshop (Erice 1986) reviewed the "Data Handling Systems" planned for large major satellites and ground experiments (VLA, HST, ROSAT, COMPASS-COMPTEL). Data analysis methods applied to physical interpretation were mainly considered (cluster photometry, astronomical optical data compression, cluster analysis for pulsar light curves, coded aperture imaging). New parallel and vectorial machines were presented (cellular machines, PAPIA-machine, MPP-machine, vector computers in astronomy). Contributions in the field of artificial intelligence and planned applications to astronomy were also considered (expert systems, artificial intelligence in computer vision).

This volume contains the proceedings of the meeting entitled, "The IGM/Galaxy Connection: The Distribution of Baryons at z = 0. " The meeting was held August 8 -10 at the National Center for Atmospheric Research (NCAR) located in Boulder, Colorado on the foothills of the Rocky Mountains (see conference photo). We organized this meeting because we felt it was time to address the link between galaxies and the intergalactic medium at low redshift. In this vein, we posed several questions to the conference participants: Where are the baryons in the local universe and in what phase do they reside? What signatures of galaxy evolution have been imprinted on the IGM? What percentage of intergalactic gas is left from the galaxy formation process? What does the distribution of baryons at z = 0 tell us about the early universe? The conference was an overwhelming success with lots of friendly interaction and discussion among the participants. At lunch we were treated to splendid views from the NCAR terrace and discussions rang ing from the importance of the LSR, GSR, and LGSR velocity frames to how long the desserts would last with 90 astronomers and the hot Boul der sun. From an inventory of the baryons, to the associations between galaxies and Lya absorbers, to the mechanisms by which galaxies obtain and lose gas, the conference covered many topics. The results of these endeavors are contained in these pages and eloquently summarized by Chris Impey.

It is with great joy that we present a collection of essays written in honour of Jayant Vishnu Narlikar, who completed 60 years of age on July 19, 1998, by his friends and colleagues, including several of his for mer students. Jayant has had a long research career in astrophysics and cosmology, which he began at Cambridge in 1960, as a student of Sir Fred Hoyle. He started his work with a big bang, expounding on the steady state theory of the Universe and creating a new theory of gravity inspired by Mach's principle. He also worked on action-at-a-distance electrodynamics, inspired by the explorations of Wheeler, Feynman and Hogarth in that direction. This body of work established Jayant's rep utation as a bold and imaginative physicist who was ever willing to take a fresh look at fundamental issues, undeterred by conventional wis dom. This trait, undoubtedly inherited from his teacher and mentor, has always remained with Jayant. It is now most evident in his untir ing efforts to understand anomalies in quasar astronomy, and to develop the quasi-steady state cosmology, along with a group of highly distin guished astronomers including Halton Arp, Geoffrey Burbidge and Fred Hoyle. In spite of all this iconoclastic activity, Jayant remains a part of the mainstream; he appreciates as well as encourages good work along conventional lines by his students and colleagues. This is clear from the range of essays included in this volume, and the variety and distribution of the essayists.

In recent years there has been a steadily increasing cross-fertilization between cosmology and particle physics, on both the theoretical and experimental levels. Particle physics has provided new experimental data from the big accelerators in operation, and data from space satellites are accumulating rapidly. Cosmology is still one of the best laboratories for testing particle theory. The present work discusses such matters in the context of inflation, strings, dark matter, neutrinos and gravitational wave physics in the very early universe, field theory at the Planck scale, and high energy physics. A particular emphasis has been placed on a new topology for spatial infinity, on the relation between temperature and gravitational potential, a canonical formulation of general relativity, the neutrino mass, spin in the early universe, the measurement of gravity in the 10--100 m range, galaxy--galaxy and cluster--cluster correlation, black holes, string theory and string/string duality. The work also presents a beautiful review of high energy elementary particle physics, treating the meaning, status and perspectives of unification and standard model gauge couplings.

The past decade has seen a considerable surge of interest in historical and philo sophical studies of gravitation and relativity, due not only to the tremendous amount of world-wide research in general relativity and its theoretical and observational consequences, but also to an increasing awareness that a collaboration between working scientists, historians and philosophers of science is, in this field, partic ularly promising for all participants. The expanding activity in this field is well documented by recent volumes in this Einstein Studies series on the History of General Relativity as well as by a series of international conferences on this topic at Osgood Hill (1986), Luminy (1988), and Pittsburgh (1991). The fourth of these conferences, hosted by the Max Planck Institute for the History of Science, was held in Berlin from 31 July to 3 August 1995, with a record attendance of some 80 historians and philosophers of science, physicists, mathematicians, and as tronomers. Based on presentations at the Berlin conference, this volume provides an overview of the present state of research in this field, documenting not only the increasing scope of recent investigations in the history of relativity and gravitation but also the emergence of several key issues that will probably remain at the focus of debate in the near future. RELATIVITY IN THE MAKING The papers of this section deal with the origins and genesis of relativity theory."

The Fourth HEIDELBERG International Conference on Dark Matter in Astro and Particle Physics, DARK2002, was held in Cape Town, South Africa, in the period 4-9 February 2002. This majestic natural area was the site of the first conference of this series (hosted since 1996 in Heidelberg) to be held outside of Germany. Dark Matter has become one of the most exciting and central fields of as trophysics, particle physics and cosmology. The conference covered, as usual for this series, a large range of topics, theoretical and experimental. Topics included Astronomical Evidence for Dark Matter, the Cosmic Microwave Background, Supersymmetry, Inflation and Dark Energy, Structure Formation, Hot and Cold Dark Matter, and Ultrahigh Energy Cosmic Rays all of which were represented by experts in the field. It was very nice to see again many of our 'old' friends in Dark Matter here in South Africa. The organizers were very glad to see, in addition to world experts, the new generation here. Many young participants gave very nice professional talks during the conference. We are grateful to John Ellis for doing an incredible job preparing his excellent summary talk during the sessions. Some special interest and intensive discussions were naturally raised by the first announcement of terrestrial evidence for hot dark matter, obtained from neutrino less double beta decay. This now adds to the evidence for cold dark matter which we have from DAM A for several years already, and which remained unchallenged up to now by other experiments.

Written by foremost experts, this short book gives a clear description of the physics of quantum black holes. The reader will learn about quantum black holes in four and higher dimensions, primordial black holes, the production of black holes in high energy particle collisions, Hawking radiation, black holes in models of low scale quantum gravity and quantum gravitational aspects of black holes.

The symbiosis between particle physics and cosmology has virtually become a conjugal relationship. Hence the 9th biennial Course of the International School of Cosmic-Ray Astrophysics was designed to bridge these formerly dispa- rate disciplines. This NATO Advanced Study Institute (ASI) took place at the Ettore Majorana Centre in Erice, Italy, June 20-30, 1992. Seventy participants from 17 countries enjoyed the opportunities for lively interactions as much as they benefitted from the stimulating lectures. This volume is based on a selection of lectures and shorter talks presented at the sessions. Warm thanks are due to my co-director, Prof. J. P. Wefel and to co-editor Dr. Rein Silberberg for their co- operation. The support of NATO's Scientific Affairs Di- vision and of Dr. L. V. da Cunha, Director of its ASI Pro- gramme, was invaluable. We also acknowledge important con- tributions by the following: Prof. A. Zichichi, Director of the Majorana Centre and its dedicated staff; the Italian Ministry of Education; the Italian Ministry of Scientific Research; the Sicilian Regional Government; the National Science Foundation of the USA, the European Physical Soci- ety, and Mrs. Shirley Ratner of Bethesda, Maryland. The Scientific Advisory Committee consisted of Profs. P. V. Auger, G. P. S. Occhialini, B. Rossi, M. M. Shapiro, R. Silberberg, J. A. Simpson, J. A. Van Allen, J. P. Wefel, and A. Zichichi. All of the foregoing persons and agencies helped make this ASI a memorable experience for the parti- cipants.

The Twenty-third Coral Gables conference on Unified Symmetry in the Small and in the Large was convened February 2-5, 1995. The shift of the traditional conference time from the last part of January was caused by the 1995 Superbowl's choice of our preferred date for their game. The conference was dedicated to reminiscences of Julian Schwinger. The death of Eugene P. Wigner in the early part of January 1995 was observed with a deep sorrow during the conference. At about that time the news of Asim Barut's death made 1995 an inauspicious year for physicists. In the meantime physics at the frontiers marched on as it did before. There were no path-breaking discoveries, but hope and persistence were still there. In 1964 (the first Coral Gables conference) if we had asked a physicist to give us a sincere opinion on what is "hot" in physics we would have expected him or her to point out the narrow area of their own research. The answer to this question in 1995 is still the same as it would have been in 1964. The mind set is a human quality and even in physics the physicist can respond like a religious believer.

The first course of the International School on Physics with Low Energy Antiprotons was held in Erice, Sicily at the Ettore Majorana Centre for Scientific Culture, from September 26 to October 3, 1986. The purpose of this School is to review the physics accessible to experiments using low energy antiprotons, in view of the new era of the CERN LEAR ring opened by the upgrade of the antiproton source at CERN (ACOL). In 1986 the first course covered topics related to fundamental symmetries. These Proceedings contain both the tutorial lectures and the various contributions presented during the School by the participants. The con tributions have been organized in six sections. The first section is devoted to gravitation, a particularly "hot" topic in view of recent speculations about deviations from Newton's and Einstein's theories. Section II covers various problems related to the matter-antimatter symmetries such as comparison of the proton and antiproton, inertial masses or spectroscopy of antihydrogen or other antiprotonic atoms. CP and CPT violations in weak interaction are presented in Section III. The test of symmetries in atomic physics experiments and the strong CP problem are covered in Section IV. Section V groups contributions related to high prec s on measurements of simple systems like protonium, muonium or the anomalous moment of the muon. The last section is devoted to the experimental challenge of polar izing antiproton beams."

From August 21 through August 27, 1989 the Nato Advanced Research Workshop Probabilistic Methods in Quantum Field Theory and Quantum Gravity" was held at l'Institut d'Etudes Scientifiques, Cargese, France. This publication is the Proceedings of this workshop. The purpose of the workshop was to bring together a group of scientists who have been at the forefront of the development of probabilistic methods in Quantum Field Theory and Quantum Gravity. The original thought was to put emphasis on the introduction of stochastic processes in the understanding of Euclidean Quantum Field Theory, with also some discussion of recent progress in the field of stochastic numerical methods. During the final preparation of the meeting we broadened the scope to include all those Euclidean Quantum Field Theory descriptions that make direct reference to concepts from probability theory and statistical mechanics. Several of the main contributions centered around a more rigorous discussion of stochastic processes for the formulation of Euclidean Quantum Field Theory. These rather stringent mathematical approaches were contrasted with the more heuristic stochastic quantization scheme developed in 1981 by Parisi and Wu: Stochastic quan tization, its intrinsic BRST -structure and stochastic regularization appeared in many disguises and in connection with several different problems throughout the workshop.

An up-to-date presentation of the progress and current problems in the early universe, cosmic microwave background radiation, large scale structure formation, and the interplay between them. The emphasis is on the mutual impact of fundamental physics and cosmology, both at theoretical and experimental (observational) levels within a deep, well- focused and well-defined programme. The nature of the domain itself leads to different aspects, approaches and points of view on the same topic. Special care has been taken to provide the reader the basis of the different, sometimes competing lines of research. All contributions are uniformly excellent, with a careful selection of the subjects and approaches covered, presenting a unifying and rigorous view of the field. Audience: experimentalists and theoreticians from a variety of backgrounds: physics, astrophysics and astronomy. An excellent reference for post-doctoral scientists. Useful for senior scientists and advanced graduate students.

"Here's a gem of a book...all peppered with delightful notes from science fiction films, novels, and comics. I can't turn a page without finding a jewel." Clifford Stoll, University of California, Berkeley, author of The Cuckoo's Egg "The research that has gone into this book is impressive." Nature "For professional physicists much of the value lies in the extensive technical appendices and footnotes, and the exhaustive list of references. But if, like me, you are a child at heart, the real fun lies in the zany stories and wild speculations." Physics World Time Machines explores the idea of time travel from the first account in English literature to the latest theories of physicists such as Kip Thorne and Igor Novikov. This very readable work covers a variety of topics including the history of time travel in fiction; the fundamental scientific concepts of time, spacetime, and the fourth dimension; the speculations of Einstein, Richard Feynman, Kurt Goedel, and others; time travel paradoxes, and much more.

Topological defects have recently become of great interest in condensed matter physics, particle physics and cosmology. They are the unavoidable remnants of many symmetry breaking phase transitions. Topological defects can play an important role in describing the properties of many condensed matter systems (e.g. superfluids and superconduc tors); they can catalyze many unusual effects in particle physics models and they may be responsible for seeding the density perturbations in the early Universe which de velop into galaxies and the large-scale structure of the Universe. Topological defects are also of great interest in mathematics as nontrivial solutions of nonlinear differential equations stabilized by topological effects. The purpose of the Advanced Study Institute "Formation and Interactions of Topo logical Defects" was to bring together students and practitioners in condensed matter physics, particle physics and cosmology, to give a detailed exposition of the role of topo logical defects in these fields; to explore similarities and differences in the approaches; and to provide a common basis for discussion and future collaborative research on common problems.

* Develops new tools to efficiently describe different branches of physics within one mathematical framework * Gives a clear geometric expression of the symmetry of physical laws * Useful for researchers and graduate students interested in the many physical applications of bounded symmetric domains * Will also benefit a wider audience of mathematicians, physicists, and graduate students working in relativity, geometry, and Lie theory

This volume contains the lectures and contributions presented at the NATO Advanced Study Institute (ASI) on "Frontier Topics in Nuclear Physics", held at Predeal in Romania from 24 August to 4 September 1993. The ASI stands in a row of 23 Predeal Summer Schools organized by the Institute of Atomic Physics (Bucharest) in Predeal or Poiana-Brasov during the last 25 years. The main topics of the ASI were cluster radioactivity, fission and fusion. the production of very heavy elements, nuclear structure described with microscopic and collective models, weak: interaction and double beta decay, nuclear astrophysics, and heavy ion reactions from low to ultrarelativistic energies. The content of this book is ordered according to these topics. The ASI started with a lecture by Professor Greiner on the "Present and future of nuclear physics", showing the most important new directions of research and the interdisciplinary relations of nuclear physics with other fields of physics. This lecture is printed in the first chapter of the book.

Recent results from high-energy scattering and theoretical developments of string theory require a change in our understanding of the basic structure of space-time. This book is about the advancement of ideas on the stochastic nature of space-time from the 1930s onward. In particular, the author promotes the concept of space as a set of hazy lumps, first introduced by Karl Menger, and constructs a novel framework for statistical behaviour at the microlevel. The various chapters address topics such as space-time fluctuation and random potential, non-local fields, and the origin of stochasticity. Implications in astro-particle physics and cosmology are also explored. Audience: This volume will be of interest to physicists, chemists and mathematicians involved in particle physics, astrophysics and cosmology.

The workshop "From Dust to Terrestrial Planets" was initiated by a working group of planetary scientists invited to ISSI by Johannes Geiss in November 1997. The group split to focus on three topics, one of which was the history of the early solar system, including the formation of the terrestrial planets in the inner solar system. Willy Benz, Gunter Lugmair, and Frank Podosek were invited to convene planetary scientists, astrophysicists, and cosmochemists to synthesize the current knowledge on the origin and evolution of our inner planetary system. The convenors raised the interest of scientists from all over the world in the detailed assessment of the available astronomical, chronological, geochemical and dynamical constraints of the first period of inner solar system evolution. In partic ular, this included appraisal of the newest results from astronomical observations by the Hubble Space Telescope, the Infrared Space Observatory, and other space and ground-based facilities of solar-like systems and nebular disks, possibly repre senting early stages of the solar accretion disk and planet formation. At the same time, the current models of the origin, evolution, transport, and accretion processes of circum stellar disks were presented. This included the new insights provided by the recent discovery of extrasolar giant planets, which were considered insofar as they are relevant to the overall dynamics of the inner part of the solar system.

Electroweak Phase Transition and the Early Universe, a NATO Advanced Re- search Workshop, was held March 23-25, 1994, at the Hotel Tivoli in Sintra, Portugal. The meeting was co-sponsored by three other Lisbon-based institutions: the Fundac;ao Gulbenkian, J. N.!. C. T. (Junta Nacional para Investigac;ao Cientifica e Tecnologica) and G. T. A. E. (Grupo Teorico de Alta Energias). The workshop brought together a large number of theoretical physicists who are actively researching topics relevant to the understanding of the standard model of electroweak interactions in the early universe. We were pleased and overwhelmed by the positive, and sometimes instan- taneous response that our enterprise raised right from its inception. The old town of Sintra provided a serene and pleasant environment for the par- ticipants. Some heated and controversial discussions on many unanswered questions in the standard model took place throughout the three days of the workshop. If one consensus emerged from the meeting, it was the imperative need for non-perturbative techniques for the understanding of the electroweak phase transition.

The reader will find in this volume the Proceedings of the NATO Advanced Study Institute held in Cortina d' Ampezzo, Italy, between July 25 and August 6, 1993, under the title From Newton to Chaos: Modem Techniques for Understanding and Coping With Chaos inN-Body Dynamical Systems. This institute was the latest in a series of meetings held every three years from 1972 to 1990 in dynamical astronomy, theoretical mechanics and celestial mechanics. The proceedings from these institutes have been well-received in the international community of research workers in these disciplines. The present institute was well attended with 15 series of lectures being given by invited speakers: in addition some 40 presentations were made by the other participants. The majority of these contributions are included in these proceedings. The all-pervading influence of chaos in dynamical systems (of even a few variables) has now been universally recognised by researchers, a recognition forced on us by our ability, using powerful computer hardware and software, to tackle dynamical problems that until twenty-five years ago were intractable. Doubtless it was felt by many that these new techniques provided a break-through in celestial mechanics and its related disciplines. And so they were.